I think this is a wonderful, brilliant idea. I have been using CanDo on my palm for years. I shun the use of categories because of several bad experiences trying to convert data from one application to another and not being able to convert the category fields.
I have been using a system of adding a simple keyword as a prefix for tasks' context (@calls, @home, etc...) and using CanDo to create saved views which filter and sort on the context keywords. CanDo allows sorting by four fields, including text, as well as filtering by keywords. Pop! for palm and TypeItIn for Windows allows easy input of the keywords as context tags.
I am now going to reorganize my lists, one of my favorite past times, to prefice items with the project tags similar to Pedja's system and enter my context keywords in notes. That way, I can still use CanDo views filtered by keyword tags that are located in the notes and also view the entire list sorted by task description so that Projects and Tasks are grouped together.
I think I will add a prefix to my project names that will allow me to filter by Roles and/or Areas of Focus. So my project names might be something like "01:Personal, Laptop: .Organize and ..." I have to be careful because I have a tendency to make the prefix wayyy to long.